The antitumor and cytotoxic activity of non-lethal fractions of animal venoms (snake, spider, gila monster, scorpion) on Yoshida sarcoma, L 1210 leukemia, Dalton's lymphoma, fibrosarcoma, Ehrlich carcinoma, and Koprowska tumor will be investigated. Normal cells such as erythrocytes, leukocytes, and bone marrow cells will be used as controls. For this study, venoms will be fractionated using a combination of ion-exchange and gel-filtration chromatography. Each fraction will be tested for lethality and the non-lethal fractions will be tested for antitumor activity and cytotoxic activity. Chemical and physical properties of the fractions with antitumor and cytotoxic activities will be extensively investigated. It is hoped that the proposed study will contribute to the long-range objective of cancer chemotherapy.